1. Field of the Invention
The present invention relates to compositions, devices, kits and methods for the detection of roundworm in animals. More particularly, the invention relates to compositions, devices, kits and methods for detecting the presence or absence of roundworm in a fecal sample. Even more particularly, the present invention relates to antibody compositions, devices, kits, and methods for detecting the presence or absence of roundworm antigen in a fecal sample that may also include one or more of hookworm, whipworm, and heartworm antigen.
2. Description of the Prior Art
Intestinal roundworm infection is common in animals and, if left untreated, can cause serious disease and even death. Although it is relatively easy to diagnosis a roundworm-infected animal as having a parasitic worm (helminth) infection of some type, it is significantly more difficult to identify roundworm, specifically, as the causative worm. This is a problem because roundworm infections are best treated when the infected animal's caregiver has knowledge that roundworm is the specific source of the infection. For example, such knowledge allows the caregiver to treat the animal with a drug that is optimally potent against roundworm, and therefore to avoid using a drug or drug cocktail that is generally effective against parasitic worm infections, but not optimally effective against roundworm.
Current methods for diagnosis of roundworm infections primarily involve microscopic examination of fecal samples, either directly in fecal smears or following concentration of ova and parasites by flotation in density media. Despite this procedure's high adoption, the method has significant shortcomings. These microscopic methods are time consuming, require specialized equipment and have low specificity. In addition, the accuracy of results of these methods is highly dependent upon the skill and expertise of the operator.
Taxonomic distinctions generally also may be made at a molecular level by determining whether one or more antigens of one or more antibodies to a particular worm species or to a defined group of worm species are present in an animal. For example, Hill et al. (Veterinary Parasitology (1997), vol. 68, pp, 91-102) disclose an enzyme-linked immunosorbent assay (ELISA) test for the detection of antibodies specific for whipworm in sera from porcine animals. While the test of Hill et al. does not crossreact with sera from pigs infected with roundworm or hookworm, it has not been determined, whether the test crossreacts with sera from pigs infected with heartworm. Similarly, Yamasaki et al. (J. Clin. Microbiology (2000), vol. 38, pp. 1409-1413) disclose an ELISA test utilizing a recombinant roundworm antigen for the detection of antibodies specific for roundworm in human sera. Whereas the assay of Yamasaki et al. has been shown to not be crossreactive with hookworm or heartworm, it has not been determined whether it crossreacts with whipworm. Bungiro and Cappello (A. J. Trop. Med. Hyg. (2005), vol. 73, pp. 915-920) disclose an ELISA to detect infection by the hookworm Ancylostoma ceylanicum in an experimental hamster model system but it has not been determined whether their test also crossreacts with one or more of roundworm, whipworm and heartworm.
Clinicians have shown little interest in using these assays to diagnose worm-infected animals. One reason why these assays have not been adopted is that researchers have not demonstrated that any of them are capable of specifically detecting a particular type of worm at the exclusion of all other major types of worms. For example, no one has yet developed an assay that specifically detects roundworm but that also has been shown to not crossreact with hookworm, whipworm and heartworm. This inability to pinpoint an animal's infection to a single source would cause uncertainty in diagnosis, and therefore would likely result in the administration of suboptimal treatment.
Further, some of these assays only have been shown to be useful for detecting antigens or antibodies in a serum sample. This is limiting because it often is impractical or difficult to obtain a serum sample from a sickened animal. For instance, in the case of an uncooperative animal, it may be difficult to stabilize the animal for the purpose of withdrawing blood, and in the case of a very sick animal, it may be impractical to transport the animal to a clinician's office for that same purpose. Testing for the presence or absence of a particular worm type therefore is better performed using an animal material that is readily obtainable and that does not require transportation of the animal, such as feces. Antigens present in fecal samples are referred to as coproantigens. In the case of the parasitic worm antigens that are subject of the present invention, coproantigens are worm antigens present in a fecal sample of a host animal.
Another limitation inherent to some of these assays is that they involve the production and purification of a specific recombinant antigen. Specifically, this is limiting because the steps required to produce and purify such an antigen can be costly and time-consuming.
What is needed therefore are compositions, devices, kits and methods for detecting the presence or absence of roundworm in a fecal sample. The needed compositions, devices, kits and methods further should be able to specifically detect the presence or absence of roundworm in a fecal sample that contains one or more of hookworm, whipworm, and heartworm.